Conventionally, there has been a technology in which a bad-running spot is created by a center, is sent to a vehicle, and is displayed on a car navigation before the arrival at the spot (for example, Patent document 1). Specifically, the center creates a shade information map in which a road condition for the formation of black ice is registered, by using the weather information and shade information that are sent from vehicles. Then, whether a request of the bad-running information sent from a vehicle is an object of the bad-running spot is discriminated by using the shade information map, and the bad-running information is sent to the vehicle. The vehicle displays a freeze warning on the car navigation before the arrival at the bad-running spot, and calculates a route on which there are few bad-running spots, in a route search using the car navigation.
Further, there has been also proposed a technology of judging the possibility of the slip of a vehicle (for example, Patent document 2). Specifically, a center-side device that receives slip position and slip-related vehicle information (for example, tire type) as slip information sends the slip information to a vehicle-side device mounted on a different vehicle. The vehicle on which a vehicle-side device is mounted acquires the slip-related vehicle information on the slipped vehicle, in addition to the position when the different vehicle slipped. Therefore, it is possible to judge whether the own vehicle slips at the position where the different vehicle slipped, in consideration of the slip-related vehicle information.
[Patent document 1] Japanese Patent Laid-Open No. 2009-26157
[Patent document 2] Japanese Patent Laid-Open No. 2009-32181